1. Field of the Invention
This invention relates to a process for producing a silicon wafer which can particularly reduce a downward bowing quantity of a portion of a wafer, which is protruded from a mounting face of a conveying blade, when the wafer is heated to a higher temperature in a treating furnace.
2. Description of the Related Art
As the conventional (100) face silicon wafer, products with a notch position indicating <011> orientation (hereinafter referred to as <011> notch product) are mainstream.
Recently, for the purpose of speeding up a device, it is started to apply products with a notch position indicating <010> or <001> orientation for using a wafer by rotating to 45 degree (hereinafter referred to as <010> notch product).
As shown in FIG. 1, the production of the (100) face silicon wafer is typically carried out by placing a (100) face wafer 3 in a treating furnace 2 of a single wafer heat-treating apparatus or a vapor phase growth apparatus 1 and then subjecting to a heat treatment or a vapor phase growth (see JP-A-10-294287).
As shown in FIG. 2, the conveying of the wafer 3 into or from the treating furnace 2 is carried out by using a conveying blade 4 having a mounting face capable of mounting only a specified region of the wafer 3 inclusive of a center position of its rear face (shadowed region S in FIG. 2).
When portions 3a of the wafer 3 protruding from the mounting face of the conveying blade 4 are heated to a high temperature in the treating furnace 2, they are thermally deformed and may bow downward from the conveying blade 4 under weight of the hanging portions of the wafer itself.
As the portions 3a of the wafer 3 are bowed downward from the conveying blade 4, when the treated wafer 3 is conveyed outward from the treating furnace 2, these bowed portions 3a may contact with members arranged around the treating furnace such as side support and the like to damage the wafer.